Answer:
The molarity of this solution is 0.0695 M
Explanation:
<u>Step 1:</u> The balanced equation
H3PO4(aq) + 2NaOH(aq) → Na2HPO4(aq) + 2H2O(l)
<u>Step 2:</u> Given data
Volume of phosphoric acid (H3PO4) = 13.13 mL
volume of NaOH = 19.64 mL
Molarity of NaOH = 0.09291 M
<u>Step 3: </u>Calculate moles of NaOH
Number of moles = Molarity * volume
Number of moles = 0.09291 M * 19.64 mL *10^-3 L
Number of moles = 0.001825 moles
<u>Step 4: </u>Calculate moles of H3PO4
For 2 moles of NaOH there is 1 mole of H3PO4 consumed to produce 1 mole Na2HPO4
So for 0.001825 moles NaOH, there is consumed 0.001825/2 = 0.0009125 moles of H3PO4
<u>Step 5: </u>Calculate molarity of H3PO4
Molarity = number of moles / Volume
Molarity = 0.0009125 moles / (13.13 *10^-3L) = 0.0695 M
The molarity of this solution is 0.0695 M